As a conventional vessel of this type, there is known the one as illustrated in FIG. 1A. This vessel 1 includes a square dish-shaped vessel body 2 which is opened at the upper part and provided with an outwardly projecting flange 3 at the peripheral edge portion of the opening. Toner 4 is received in this vessel body 2. A cover sheet 5 is folded upon itself at its rear (rightward) edge to form a double thickness and thus comprises a lower part 6 and an upper part 7, the former covering the opening, and the latter, which is superposed on the former, extending its fore end part 8 outside of the flange 3.
When the conventional toner vessel of this type is turned upside down and applied to a conventional copying machine (not shown) for use, as shown in FIG. 1B, the sheet 5 is peeled off from the flange 3 by pulling the sheet in the direction of the arrow with the end part 8, and thus the opening of the body 2 is gradually opened, whereby the toner 4 received in the vessel is allowed to fall on the developing area of the copying machine.
The conventional vessel of this type, however, was defective in that upon peeling the lower part 6 of the sheet 5 from the flange 3, the part 6 must be pulled out of the vessel 2, but the toner 4' adhered to the back of the lower part 6 tends to fall, at that time, onto portions inside or outside of the copying machine other than the developing area, thereby staining those portions.